Improvement in screw-fastenings



4 J'. o. AHLs'TRoM'.

. SCREW-FASTENING.

No.170,041. Patenteqmm 16,1875.

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IMPROVEMENT |N scREw-FA'stENlNGs.

Specilication forming part of Letters Patent N o. 170,041, Vdated November 16, 1875; application filed August 30, 1875.

To all whom it may concern:

Be it known that I, Jnsrna O'rro AHL- STROM, ot' Williamsburg, Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Screw-Fastenings; and I do hereby declare that the following is a full, clear, and exact description ofthe same, reference being had to the accompanying drawing, which forms part of this specilication.

Thisinvention relates to screw-tastenings applicable to securing brackets or other articles to masonry, and forother purposes, ofthe kind described in Letters Patent No. 13,17 7, issued to John London and Otto Ahlstrom, July 3, 1855. In such devicea screw-bolt has its head constructed'of iixed wedges and loose expanding side pieces, whereby the act of screwing up the nut is caused to expand the said head, for the purpose of makingV it t tightly'in a suitable cavity or hole, in which it is placed 5 or, as an equivalent, the nut is constructed-'with said fixed wedges and expanding side pieces, so that by screwing in the bolt it may, inf the same manner, be expanded to t tightly within the cavity whichA receives it. Furthermore, an elastic ring serves to keep the expanding side pieces always in a condition to use on the bolt or nut, and allows them to expand when the nut or bolt is screwed up, and to contract when the nut or bolt is unscrewed for the purpose ot' removal.

My improvement consists in a combination, with the lixed wedgeson the bolt-head or nut at the one end ot' the expanding side pieces, of supplementary and sliding wedges at the opposite end ot' said side pieces, whereby not only the expanding' side pieces are equally expanded throughout their length and at their opposite ends, but whereby either a pull or blow on the screw-fastening in direction of its length will serve to keep the expanding side pieces parallel, and tight as regards their lit within the cavity which receives them, thus rendering the screw-fastenin g more secure than under the old or former construction, hereinbefore referred to. v

Figure 1 represents a partly-broken longitudinal view of my improved screw-fastenin g,

` having the fixed wedges applied to the head ofthe bolt 5 and Fig. 2, a longitudinal or side View of the same at right angles to the former gure. Figs. 3 and 4 are similar views to Figs. 1 and 2 of the improvement when the ixed wedges are applied to the nut and a part thereof. Fig. 5 is a transverse section on the line w and Fig. 6 a transverse section on the line y y. Fig. 7 is a View showingthe application oftheimproved screw-fastening, constructed as represented in Figs. 1 and 2, to the securing of a bracket on or against a wall.

Referring, in the first instance, to Figs. l, 2, and 7 of the drawing, b. b represent the fixed double wedge fast on the head or one end of the bolt B, and c c the loose expansible side pieces, held together by an elastic ring, d, so that on screwing up the nut C of the bolt,

said side pieces are caused to expand, and to t tightly within thc cavity in the wall or masonry within which lthey are placed, and so that by unscrewing thenut the expanding side pieces are unloosed to` admit of the removal of thel fastening, all as hereinbefore described with reference to the patented device of London and Ahlstrom. VIn that construction, however, so far as described, the torce to expand the side pieces c c is exerted by the double wedge b b at their one end only, which prevents'a uniformity of expansion throughout the length of said side pieces, and a blow upon the bolt to force it farther into its cavity relieves the doubleI wedge b b, and allows of the side pieces contracting, so that the screwfastening becomes loose. These defects are obviated by providing the bolt at the opposite end ofthe expansible side pieces c c with a free or sliding double wedge or follower, composed of wedges ff, which enter within the expansible side pieces c c at the outer or opposite end of the latter to the fit of the double wedge b b, sothat not only on screwing up the nut O will the expansible side 'pieces c c be forced out equally from both ends, but so that either a pull or blow on the screw-fastening in direction of its length will serve to tighten the expansible side pieces, orto keep them taut within the cavity in which they fit, and to preserve the parallelism of the side pieces throughout their entire length, thedouble wedge f f actingas a follower to produce such effect.

The same effect or effects are produced when 2 v I n 70mm the fixed double Wedge b b is applied to the l v The combination of the supplementary and nut, as in Figs. 3 and 4, in Which B also repfree double Wedge or folloWe'xl f f with the resentsthe bolt,thatmayhaveacommon head; double wedge b, the expansible side pieces c c, the expansible side pieces; d, the elastic c c, and the bolt B, substantially as speoied.

holding-rino' and ff the supplementary and e free doublebivedge or follower at the opposite EbPER OTTO AHLSTROM' end of the eXp-.msible side pieces to that With- Witnesses: in which the double Wedge b b of the nut ts. ,BENJAMIN W. HOFFMAN,

I claim- FRED. HAYNES. 

